public void Enqueue(WorkItem item)
                    {
                        this.UpdateLastAccessTime();

                        // Project work
                        item = item.With(documentId: null, projectId: item.ProjectId, asyncToken: this.Processor._listener.BeginAsyncOperation("WorkItem"));

                        var added = _workItemQueue.AddOrReplace(item);

                        Logger.Log(FunctionId.WorkCoordinator_Project_Enqueue, s_enqueueLogger, Environment.TickCount, item.ProjectId, !added);

                        SolutionCrawlerLogger.LogWorkItemEnqueue(this.Processor._logAggregator, item.ProjectId);
                    }
                    public void Enqueue(WorkItem item)
                    {
                        Contract.ThrowIfFalse(item.DocumentId != null, "can only enqueue a document work item");

                        // we only put workitem in high priority queue if there is a text change.
                        // this is to prevent things like opening a file, changing in other files keep enqueuing
                        // expensive high priority work.
                        if (!item.InvocationReasons.Contains(PredefinedInvocationReasons.SyntaxChanged))
                        {
                            return;
                        }

                        // check whether given item is for active document, otherwise, nothing to do here
                        if (_processor._documentTracker == null ||
                            _processor._documentTracker.GetActiveDocument() != item.DocumentId)
                        {
                            return;
                        }

                        // we need to clone due to waiter
                        EnqueueActiveFileItem(item.With(Listener.BeginAsyncOperation("ActiveFile")));
                    }
                    public void Enqueue(WorkItem item)
                    {
                        this.UpdateLastAccessTime();

                        // Project work
                        item = item.With(documentId: null, projectId: item.ProjectId, asyncToken: this.Processor._listener.BeginAsyncOperation("WorkItem"));

                        var added = _workItemQueue.AddOrReplace(item);

                        // lower priority queue gets lowest time slot possible. if there is any activity going on in higher queue, it drop whatever it has
                        // and let higher work item run
                        CancelRunningTaskIfHigherQueueHasWorkItem();

                        Logger.Log(FunctionId.WorkCoordinator_Project_Enqueue, s_enqueueLogger, Environment.TickCount, item.ProjectId, !added);

                        SolutionCrawlerLogger.LogWorkItemEnqueue(this.Processor._logAggregator, item.ProjectId);
                    }